[ntp:questions] Re: ntp servers reporting leap second erroneously?

Martin Burnicki martin.burnicki at meinberg.de
Tue Oct 25 12:03:37 UTC 2005


Terje Mathisen wrote:
> Martin Burnicki wrote:
>> Under Linux, the leap second announcement is passed to the kernel which
>> handles it properly.
>> Under Windows, the time is stepped back by one second a few minutes after
>> the time of leap second insertion.
> If nobody else volunteers I'll take a look at the Win source code and
> see if I can figure out a reasonably good way to insert/delete a second
> by an extra clock slew that avoids resetting the clock drift value.

The problem that the time is stepped back by one second a few minutes after
the time of leap second insertion should be the same for all operating
systems which have a sytem clock which is not aware of leap seconds.

So I think the preferred way to solve this would be to add this feature to
the global code which is compiled on such systems. That piece of code is
managed by Dave, so I'd primarily appreciate if Dave would implement this.

Dave, is there a chance you could do this? I'm sure it would be appreciated
by lots of people.

>> As I've reported earlier on this news group even the Windows w32time
>> service is capable to slew the Windows system clock at UTC midnight to
>> compensate the leap second offset in just a few seconds.
> Which is why I'm willing to dig in. :-)

If Dave is not willing to implement this it would be great if you could dig
in to implement it as a Windows-specific workaround. 

> "Anything Microsoft can do, we can do better."

That should be our goal ;-)

There are lots of instances of ntpd running under Windows today. In this
newsgroup we keep telling users that ntpd for Windows works better than
w32time. Should we accept now that w32time, which has not been aware of
leap seconds at all for a long time, can handle leap seconds much more
gracefully than ntpd?

Ntpd simply steps time back and we all know that this is not a good thing.

Anyway, if you or Dave would implement a way to handle leap seconds better
on systems like Windows, and if you don't have the chance to test the code,
I'll be happy to do that using the simulator I have here.

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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